This invention relates to dual in line packaged (DIP) devices and, in particular, to a circuit modification device that allows replacement of a DIP with a similar sized enhancement in an existing fielded piece of equipment.
DIP devices, such as large scale integration components, e.g. microprocessors and the like, are completely packaged by the manufacturers and in-circuit modifications (modifications within the packaged circuit itself) heretofore have not been possible. Currently, in order to change a chip junction in a circuit that is already fielded it is necessary to either rebuild the entire circuit or discard and replace valuable still useable components. One current problem is that of fixed address space in microcomputers. For instance, it is not presently possible to remap the memory in a TRS-80 microcomputer without bulky hardware modifications. It is also desirable to add logic functions by means of integrated circuit (IC) components. The reconfiguration of computer memory and the addition of IC circuit components therefore currently entails extraneous circuit additions, relatively long lead lines, and additional space requirements. These, in turn, result in additional problems. For military applications, where rugged fixed in position components are required hard soldering of all of the electronics necessary to implement the required hardware modification is not always possible. In other aplications the additional length of lead lines can cause problems in operation because of timing pulse delays. Such long wire additions introduce electrical emanation problems as well as inter circuit capacitance and inductance which could produce errors in processing. Furthermore, such additions are expensive and do not meet manufacturer's specifications for size, space and power. The current practice is to replace rather than upgrade existing equipment. The economic price paid for this approach is obvious and sometimes prohibitive. There currently exists, therefore, the need for a DIP circuit modification device that can provide in-circuit reconfiguration of fielded components inexpensively and in compliance with manufacturers size, space and power specifications. The present invention is directed toward satisfying that need.